Hostage Taker of Quads

Just make sure all the paper gets covered -- may just be my brush technique (or lack there of) but I usually miss spots and it shows as whiter paper streaks. go over it again, an it takes on a uniform tone.

Dedicated foam bender

Like Dan said, the foam doesn't need it, but hitting the edges seems to help with keeping the paper from peeling off. It's really up to you, and you can experiment on some scrap to see if makes any difference, and it will also help give you some practice with technique.

FT CAD Gremlin

I have built 2 planes that I treated with minwax (both Bloody Wonders) and many others that were not. Has anyone else experienced that the foam core seems to get much more brittle after minwax treatment. What I have noticed is that treated foam compresses much easier and does not return to it's previous thickness, whereas untreated foam is much harder to compress and will return to almost the original thickness if compressed. I also believe that the skewers holding the front of the power pod in tore out with minimal force in the treated planes vs. the untreated planes. Anyone else seen this?

I'm trying the minwax again on a FT Spitfire. I've applied the minwax as light as possible. We'll see how this one turns out.

Dedicated foam bender

Most likely what you are experiencing is that the treated board is harder and therefore more brittle. Bare paper has more flex than the treated and therefore more "give". I have noticed tape seems to give protection and strengthening properties without making the board brittle. Unfortunately, the Spit isn't the best platform for tape covering.

Member

I was wondering, since Minwax is a clear acrylic coat, if anyone has tried a spray version. Krylon and a couple of others companies make a clear acrylic sealant. I've used it for years in art projects and was planning on using it for my planes. I'll be testing it out for myself, but was just wondering if anyone else has already tried it.

Senior Member

If you are using the non-waterbased polyurethane that David recommends, I believe that stuff will dissolve the foam. Probably best to try to keep it off the edges. The water based polyurethane is completely foam-safe.

If you are looking to seal the edges try hot glue. The method I use is to put a dollop of hot glue towards the side of a small scrap piece of foam and smear it around the edges. Seems to add a lot of resilience and keeps the paper from peeling up.

I have a dual temp hot gun. The low setting is barely enough to melt multi-temp glue stick, and the hot setting is so hot that it will melt the foam if I am not careful. I use the hot setting for this so the dollop stays liquid for a long time. The high temp glue seems to seal the edge especially well, but doesn't melt it because the very thin film you leave behind cools rapidly.

This is also a great way to seal the exposed foam on your control hinges.

Posted a thousand or more times

If you are using the non-waterbased polyurethane that David recommends, I believe that stuff will dissolve the foam. Probably best to try to keep it off the edges. The water based polyurethane is completely foam-safe.

If you are looking to seal the edges try hot glue. The method I use is to put a dollop of hot glue towards the side of a small scrap piece of foam and smear it around the edges. Seems to add a lot of resilience and keeps the paper from peeling up.

I have a dual temp hot gun. The low setting is barely enough to melt multi-temp glue stick, and the hot setting is so hot that it will melt the foam if I am not careful. I use the hot setting for this so the dollop stays liquid for a long time. The high temp glue seems to seal the edge especially well, but doesn't melt it because the very thin film you leave behind cools rapidly.

This is also a great way to seal the exposed foam on your control hinges.

In the video, the FliteTest guys specifically recommended against using the water-based Minwax. They use the oil-based Minwax on all their planes. A lot of people have successfully used the oil-based version. See the link below.

Hostage Taker of Quads

A lot of builders use the waterbased but only *AFTER* stripping off the paper. for the stripped foam it's used as a poor-to-fair surface skin, a good primer coat, or an excellent lamination glue (be sure to compress the pieces for *at least* 12 hrs)

If you want to build using unstripped foam board, waterbased cannot be used, since it will cause the paper to warp and separate from the board.

All of FT's builds are with the paper left on, so for a FT build, use the oil-based.

Hot glue edgings and joints are pretty nice, but take some skill and a quick hand to apply, squeegee, and clean up -- all before the glue cools and all without getting a second degree burn :black_eyed: It's not a bad technique, but practice a couple of times on a long scrap piece before you try it on your airframe-in-progress

Member

I recently applied the minwax treatment to my FT Racer, and I happened to cover the edges as well. It went on fine. One added benefit I can think of for applying to the edges is that when it comes time to paint, your edges will be protected from the evils of rattlecan spraypaint damage. It's not the paint, it's the propellent in the can that can, nay will eat your foam if applied too close to the surface. Apply the minwax in a ventelated area if you can...after half an hour in the garage, I forgot math....

New member

craftyDan, the way i do my edges, thats if i remember to hot glue them is to run a super thin bead of glue down the edge then i smear it out using the side of the nozzle of the hot glue gun, it keeps the glue hot and runny as you're smearing it. makes it super simple

Hostage Taker of Quads

craftyDan, the way i do my edges, thats if i remember to hot glue them is to run a super thin bead of glue down the edge then i smear it out using the side of the nozzle of the hot glue gun, it keeps the glue hot and runny as you're smearing it. makes it super simple

Junior Member

Being from California I can only get water based poly. Has anyone tried SPAR urethane? Would it be an acceptable substitution? If not are there other good options. Where I live it is cold and wet during the winter and over 100 during the summer and I want them to last.
Thanks

Dedicated foam bender

I used the spar urethane in a spray can on my spit. I wasn't thrilled with the results as it seems to still let the humidity peel the paper from the foam. It does help but it just isn't the same as the minwax treatment